1. Field of the Invention
This invention relates to an adjustable concrete or mortar screed rail for guiding a screed for the purpose of leveling the poured concrete or mortar to a desired height so as to control the thickness of the concrete or mortar to be applied. This device then becomes a metal reinforcement of the concrete or mortar bed.
In the past, the process of laying concrete or mortar has involved dividing the floor into rectangles of equal size. Half of these rectangles, distributed in a chessboard pattern, are laid the first day and the remaining half are laid the second day, since the sides bounding these rectangles are used as a screed guide support for the apparatus which is used for leveling the applied concrete or mortar. Every second section must be given sufficient time to harden before the adjacent sections can be treated in the same way. The arrangement-forming boundaries for the sides of the rectangular sections also act as barriers for the freely running concrete or mortar.
Conventionally, sand is often used as a base on which screed guide supports can be placed so that they are horizontal. When the screed guides are in position, concreting can be carried out in the first-day rectangles. The concrete is poured in the rectangles in question and is leveled off manually. When all the first-day rectangles have been processed, work is stopped to give the concrete time to harden until the next day. The same screed guide supports can be used on the following day for proceeding in an analogous manner.
As shown in FIG. 8, most tile contractors currently use a wood float strip application which involves setting a 11/2 inch by 1/8-inch wood strip 46 on a previously applied row of mortar 48. Wood strip 46 is pressed into place and leveled to a height of 11/4 inch above plywood subfloor 50 while mortar row 48 is still soft. Thereafter, mortar 52 is poured to a height of 11/4 inches, the poured mortar 52 forming a cold joint 54 with the previously-applied mortar row 48. Some of the problems involved with wood float strip application include the fact that the cold joints 54 almost always crack with ease, it is difficult to keep edges of the wood 46 level, and the process takes 4-5 times longer than when using the adjustable screed rail of the invention.
2. Description of Related Prior Art
Screed guides, including adjustable screed guides, are known in the prior art. U.S. Pat. No. 4,598,517 issued Jul. 8, 1986 to Yngve Alvarsson discloses a unitary screed guide having upper and lower flanges for the purpose of resting flatly on a base, the web joining the flanges having openings therein to allow the passage therethrough of reinforcing rods. Also disclosed therein are ring-shaped screed guides to surround ceiling support pillars. The disclosed screed guides are not individually adjustable other than by changing the level of the base supporting the screed guides.
U S. Pat. No. 4,707,955 issued Nov. 24, 1987 to John D. Clapson discloses a variety of unitary screed rails which are adjusted vertically by means of spacers. U.S. Pat. No. 4,727,690 issued Mar. 1, 1988 to Keith Honeyman discloses a unitary screed rail designed to rest on an underlying surface which may be formed by bare soil or concrete. U.S. Pat. No. 4,884,384 issued Dec. 5, 1989 to Stig-Ake Ljungkvist and Lennart Johansson discloses a unitary screed guide or rail formed as an I-beam, vertical adjustment being provided in the form of sand U.S. Pat. No. 4,909,002 issued Mar. 20, 1990 to Roy A. Clifton and Terry J. Stoner discloses unitary screed rails of various shapes formed of concrete.
U.S Pat. No. 4,945,698 issued Aug. 7, 1990 to Jeffrey R. Jertberg et al. discloses an adjustable screed guide or rail formed of two elements which are adjustable relative to one another. The screed guide or rail, while disclosed to be used during screeding of cement on a wall, may be used in the formation of floors. The screed rail or guide is formed of an angled bar which is attached by wood screws to a wall or subflooring, and a flat bar which is adjustably mounted on the angled bar by bolts and nuts, the flat bar having a flat edge upon which a screed rides, and holes through which strengthening wires and/or concrete or mortar may be passed.